GB251588A - Improvements in or relating to amplifying or detecting relays - Google Patents

Abstract

251,588. Soc. d'Etudes pour Liaisons TÚlÚphoniques et TÚlÚgraphiques Ó Longue Distance. May 4, 1925, [Convention date]. Am.plifying systems. - A network of impedances comprising an adjustable resistance in parallel with a tuned circuit or a system of tuned circuits is included in the reactive coupling between the input and the output of a relay so that the phase differences between the input voltage and the reactive voltage is greater than 90‹ so as to diminish amplification for the frequency or frequencies it is desired to choke. Fig. 3 shows an arrangement adapted to choke all frequencies except one to which the circuit 14, 15 is tuned. Fig. 4 illustrates a similar arrangement in combination with an arrangement as described in Specification 243,765 which is adapted to produce a reactive voltage less than 90‹ out of phase with the applied voltage through transformer 16. The circuits 18, 19 and 22, 23 are tuned to the frequency to be favourized and the coupling through transformer 20 induces voltages more than 90‹ out of phase with the applied voltage. In a modification a simple back-coupling transformer is employed and the network so arranged that the reactive voltage at certain frequencies is in phase but for other frequencies is more than 90‹ out of phase with the input voltage. The Specification as open to inspection under Sect. 91 (3) (a), also comprises the use of a single coupling resistance as the impedance included in the reactive coupling. This subjectmatter does not appear in the Specification as accepted.